1. Technical Field
The present invention relates to an apparatus for manufacturing a long-period optical fiber grating.
2. Related Art
An optical fiber communication system consists of an information source, a transmitter or modulator, a transmission medium, and a receiver or demodulator at a destination point. The information source provides an electrical signal to the transmitter. The transmitter comprises an electrical stage which drives an optical source to give modulation of the light-wave carrier. The optical source which provides the electrical-optical conversion may be a semiconductor laser. The transmission medium consists of an optical fiber cable. The receiver consists of an optical detector which drives a further electrical stage and hence provides demodulation of the optical carrier. Thus there is a requirement for electrical interfacing at either end of the optical link. Fiber optic communications offer major advantages over wire systems because of low attenuation and high bandwidth available.
An optical fiber cable is an optical fiber waveguide having a core of a first refractive index n.sub.1 surrounded by a transparent cladding of slightly lower refractive index n.sub.2. The cladding supports the waveguide structure while also substantially reducing radiation loss into surrounding air. The optical fiber cable corresponds to a single cylindrical glass fiber having a diameter comparable to the diameter of a human hair. The optical fiber cable acts as an open optical waveguide. Light which is launched into an optical fiber at an angle less than an acceptance angle demonstrate total internal reflection in the core of the optical fiber. Periodic structures maybe incorporated into planar waveguides to form integrated optical filters. An optical filter can be used to guide light to the core of an optical fiber causing the light to propagate in the core of that optical fiber.
One type of optical filter is a long period grating filter. I have found that there is a need for an improved apparatus for manufacturing long-period optical fiber grating. Efforts have been made to improve optical fiber-related components.
Exemplars of recent efforts in the art include U.S. Pat. No. 5,596,442 for BRAGG REFLECTION GRATINGS IN OPTICAL FIBERS issued to Byron, U.S. Pat. No. 5,951,881 for FABRICATION OF SMALL-SCALE CYLINDRICAL ARTICLES issued to Rogers, et al., U.S. Pat. No. 5,912,999 for method for FABRICATION OF IN-LINE OPTICAL WAVEGUIDE INDEX GRATING OF ANY LENGTH issued to Brennan, III, et al., U.S. Pat. No. 5,898,804 for OPTICAL FIBER HAVING CORE SEGMENT WITH REFRACTIVE-INDEX GRATING issued to Wickham, U.S. Pat. No. 5,881,188 for OPTICAL FIBER HAVING CORE SEGMENT WITH REFRACTIVE-INDEX GRATING issued to Starodubov, U.S. Pat. No. 5,787,213 for METHOD AND APPARATUS FOR WRITING BRAGG GRATINGS ON STRAINED OPTICAL FIBERS issued to Brownlow, and U.S. Pat. No. 5,620,496 for METHOD OF MAKING STABLE OPTICAL DEVICES EMPLOYING RADIATION-INDUCED INDEX CHANGES issued to Erdogan, et al.
While these recent efforts provide advantages, I note that they fail to adequately provide an improved apparatus for efficiently and conveniently manufacturing long-period optical fiber grating.